358 INFERIOR OOLITE AMMONITES. 
of terms by which a more complete analysis of specific characters and their 
biological significance can be stated with greater precision, and in fewer words, 
than has hitherto been in any degree possible. With these terms the characters 
of these forms can be stated thus : 
Species. Brephic stage. Neanic stage. Ephebie stage. 
S. subspinosa Regular spines Plain ribs, and at intervals Plain ribs, and at intervals spined 
spined ribs (irregular ribs (spinicoste), declining to 
spinous stage) knobbed ribs (nodicoste). 
S. decorata Do. Cost and spinicoste Coste and nodicoste, followed 
by plain coste. 
S. subdecorata Do. Do. Coste. 
S. decora Dor In the early part cost and Coste. 
nodicostz, later costz only 
From this table the earlier inheritance of the ornamentation of the ephebic 
stage of subspinosa may be traced until this ornament appears in the early neanic, 
or perhaps even late brephic stage of S. decora, which stage is thus the morpho- 
logical representation of ephebic subspinosa. All the species show various 
phases of phylocatabatic development after their brephic stages. The decline 
becomes very pronounced in S. decora; but the phylhypostrophic stage is not 
reached in this stock, because by analogy with other series it may be known that 
the form belonging to that stage would be smooth and keelless. 
The species of the subdecorata-stock are the morphological equivalents, on 
a small scale, of S. crassispinata a, irregularis, submargimata, and subcostata. 
That they are not the young of these species may be seen by certain external 
differences of ornament and proportion. That they belong to a stock very 
different from submarginata may be learnt from the possession of a longly- 
lobate suture-line in correlation with the costate stage—for instance, in subdeco- 
rata. This suture-line, so different from that of submarginata, indicates that the 
subdecorata-stock is only distantly related thereto, but that it is nearly allied to a 
series which will be described presently. In regard to descent the subdecorata- 
stock will appear to be a separate derivation from multispinata, or from the 
morphological equivalent thereof. 
Sonnrnta susspinosa, S. Buckman. Plate XLIX, figs. 8, 9; Plate LXXXIV, 
figs. 4—6. 
Discoidal, compressed, hollow-carinate. Whorls ornamented in the brephic 
1 Details obscured by tool during removal of matrix. 
